Jellyfish Surface In Washington Lake Sting Not Harmful To Humans In Tiny Freshwater Species

Eleven-year-old Brandi Scollard was getting ready for a swim in John Sam Lake last week when she spotted the jellyfish.

“She moved the paddle boat and all of a sudden, they just started coming to the surface - this pulsating kind of white mass,” said Brandi’s grandmother, Paula Salzbrun.

Salzbrun told Brandi to stay out of the lake, which is northwest of Marysville. Then Salzbrun started to call around for information.

Brandi captured several jellyfish in a jar for a closer look. They ranged in size from a dime to a quarter, and had white, translucent bodies with a ring of tentacles.

Salzbrun, who has lived on the freshwater lake for seven years, called every government agency listed in her telephone book with “water” or “marine” in its name, but got no information.

So she turned to a computer encyclopedia and confirmed there is a type of jellyfish that lives in fresh water.

Craspedacusta sowerbii was first noted in the United States in 1908, according to “The Freshwater Invertebrates of the United States” by Robert W. Pennak. They are most often found in small lakes, ponds and old water-filled quarries between the months of July and October.

There have been few reported sightings of large numbers, or blooms, of jellyfish in Washington state.

Harry Gibbons, program manager for lake restoration and water quality services at the Seattle consulting firm KCM Inc., said the bloom at John Sam Lake is the first he’s heard of in the Puget Sound area.

Heavy jellyfish populations could be linked to recent flooding, said Gibbons, who is also the on-call freshwater expert for Snohomish County’s Surface Water Management Division. The wet weather last winter and spring may have triggered the bloom in John Sam Lake.

“They’re cute little devils,” Gibbons said, adding that he believes their appearance in the lake is a good sign.

“It indicates there’s a healthy population and diversity of organisms,” he said. “So many systems have sediment problems that destroy habitat. This is a sign that this lake isn’t receiving a large amount of sediment.”

Terry Peard, a professor of biology and science education at Indiana University of Pennsylvania, studies jellyfish and has even devoted a Web site to answering questions about them.

The jellyfish have been found in all kinds of aquatic environments and are known to exist around the world and in at least 35 states, he said.

So what can people living along John Sam Lake expect?

The jellyfish will disappear within a couple of weeks and may or may not reappear, Peard said. Larger fish may eat them, but smaller minnow-sized fish feel their sting and spit them out.

The good news is their sting isn’t harmful to humans.

That’s reassuring to Salzbrun and her granddaughter. Now that Brandi has learned what they are, the sixth-grader at Marysville Middle School might do an extra-credit science report, using the laboratory at her doorstep.

“In a way,” she said, “it’s cool.”